


Just Keeping You In Check

by liketogetlost



Category: Supernatural
Genre: F/M, Sibling Incest
Language: English
Status: Completed
Published: 2013-01-01
Updated: 2013-01-01
Packaged: 2017-11-23 05:32:27
Rating: Explicit
Warnings: Underage
Chapters: 1
Words: 2,416
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/618645
Author URL: https://archiveofourown.org/users/liketogetlost/pseuds/liketogetlost
Summary: <blockquote class="userstuff">
              <p>He's watching Sam. Out of the corner of his eye, between the endless stretch of blurring pavement in front of him and the gas gage, is Sam with her long limbs that threaten to poke out the car windows and her long, wild mane of hair that always seems to be in her face, caught on the wind and waving like a flag.</p>
            </blockquote>





	Just Keeping You In Check

**Author's Note:**

> Sam's always been a girl, she's fifteen and yes I know, I'm headed to the pit.

Dean's watching Sam. He's always watching Sam, has been since their dad placed her in his arms. But it's past two am, and his eyes are heavy with the events of the day and he can't let himself sleep until she does. Digging up the graves of five different angry spirits that all hung out together fifty years ago only to decide friends forever really did mean forever was hard work. Sam was shit with a shovel but at least she helped salt and burn the bones.

It's a habit, a thing he's done since they were kids, and he'll just continue to jerk awake until he knows she's out so there's no use just letting himself drift off. But tonight Sam can't sleep, which means Dean can't sleep.

His weight is heavy on top of the worn springs of the hotel mattress, but he's exhausted and even the lumps beneath him feel comforting against his tired muscles. The night is quiet save for the phantom sounds of the highway and the few cars that drive in and out of the parking lot outside. Sam's legs rustle beneath the sheets of her bed, unshaved and rough against the cheap fabric and he can almost feel her frustration as she tosses and turns for the umpteenth time that hour.

He's about ready to reach over and turn on the light when he catches the sight of her hand snaking beneath her sheet and burrowing down to her waist.

He thinks she's probably just scratching her stomach until he hears her restrained sigh, almost inaudible against the whir of the air conditioner at the window.

Sam touches herself, jerks off, masturbates, whatever. He knows this, he's not stupid. She's a teenage girl, and whether guys think so or not girls enjoy sex too. But it's not something he likes to think about in relation to Sam. But there it is, in the bed next to him, just two feet of crud covered motel floor separating him from this Sam. This Sam who's...

Who's just let out a small moan that hits him right in his stomach and makes him harder than anything. He thinks it's probably time to close his eyes, probably find a way to cover his ears too but his eyes are greedy and they feed on the sight of the tell tale movement of her wrist beneath the sheet, the silhouette of her against the light that hits the back wall, the bit of the sheet he can see through when she arches her back above the bed.

His throat convulses and he swallows, mouth suddenly dry and his tongue thick in his mouth like he should say something, tell her to keep her hands above the covers for the night, Sammy, haha no big deal like he can make a joke of it. But he doesn't want to, wants to keep watching, wants to see her, oh fuck, _hear_ her come and it makes him feel sick and hot beneath the thin blanket all at once.

So he watches Sam. Watches her black outline shift in the dark, her muscles tensing and relaxing beneath her skin. He watches her chin poke the air, head tossed back at a particularly effective stroke of her fingers. He thinks he sees a flash of her tongue but he can't be sure, but it's likely, swiped across her bottom lip when the tension inside her begins to coil in her belly and spread out through her body like vines from a tree.

He keeps watching and when her throat cracks like she wants to scream but can't, and her foot digs into the mattress and slips across the sheet and off the side of the bed, he grips his pillow beneath his head and tries to hold in the deep breath he so desperately needs to let out.

He doesn't quit watching until the speeding swell of her chest dies down to normal, and she slides rather than flops onto her side facing away from him and he hears the first soft snore from her mouth that means she's asleep.

He's left with hard on that actually hurts and a pool of sweat that makes his t-shirt stick to his lower back. Left watching as she sleeps, watching her grow up before his eyes.

\--

He's watching Sam. Out of the corner of his eye, between the endless stretch of blurring pavement in front of him and the gas gage, is Sam with her long limbs that threaten to poke out the car windows and her long, wild mane of hair that always seems to be in her face, caught on the wind and waving like a flag. Her nose is stuck between the pages of a book, something about animals and a farm, she'd told him it was some kind of satire, whatever that meant. The wind whips the pages so she has to hold the book flat against her lap. 

It's hot, and Sam would say 'duh, it's the desert', but this heat comes from deep inside him and seeps out of his pores like lava from a volcano. He wishes there was more space between them on the front seat of the Impala.

“Quit looking at me.” Sam says, eyes still glued to the page and scratching at a bug bite on her knee. Her feet are pressed to the glove box and her fucking legs, stuck out the bottoms of a pair of his old jeans she cut into shorts, are so long her knees practically push into her face. She's always growing, she's almost taller than him for chrissakes, awkward and gangly but something inside tells him she would have been a ballerina, if not for everything.

“I'm not.” He can't even come up with a clever quip because he is, actually.

“Whatever.” But there's a smile in her voice. She picks at another bug bite that's scabbed over and collects the skin and blood beneath her nails.

“Don't pick at those, you'll leave scars.” He says absently, automatically. Like a father.

She rolls her eyes which he doesn't see but she's fifteen, she's always rolling her eyes. “Not like I don't have enough of those.” She mutters, low in her throat but loud enough so he can hear like she really wants him to.

His eyes are burning, probably red and dry from the desert air. A sigh escapes him, and he's turning off the pavement to stop on the abandoned slice of earth next to the road. “I need a fucking nap.”

She throws her book on the dash and laughs, the sound of which is muddled by the sound of a freaky sounding bird in the distance and she turns for a second to hear it's next cry. Seconds pass and it doesn't speak again, and when she looks over he's hunched down in the seat with his arms crossed over his chest and his eyes closed.

“Figures you're tired, fucking peeping Tom.” It's mumbled but again, it's not like she doesn't want him to hear.

The heat is bubbling inside him again when he cracks open an eye in her direction. “What?”

“I couldn't sleep, alright? It's not like I wanted an audience.” She wants him to think she's actually pissed, but he sees the crook of her smile in the sideview mirror next to her.

“Sam, just. Shut up and take a fucking nap, okay? We got a long way 'til we hit dad's new coordinates in Arizona.” He checks to make sure his shotgun is safe in the backseat just in case and shuts his eyes again. 

He jumps, ready to grab for the gun when he feels a weight on his lap. A knot tightens in his stomach when he opens his eyes to Sam, legs straddling him, the pink of her breasts, still small but growing, visible through a thin layer of cotton wife beater and practically in his face. 

Her eyes are set on him, big and brown and serious, which is how she usually looks when she's trying to appear brave. The sunkissed locks of her hair are in tangles around her face and her lips are still red from the fruit punch she got from the gas station miles back. She stirs him like a spoon in a cup of coffee and he's drowning, he can't breathe.

“Sam. Get off.” Is not what he wants to say, but does.

Her smile is almost feral, and wide, from ear to scarred ear. “I did, last night.”

His eyes roll but his stomach clenches and he grabs her by the waist to pull her off. She's ahead of him, hands gripping the back of his seat, and she winds up settled against him closer, thighs trapping him and arms that go on forever creating a bastardized fence around him.

“You wanna watch me, Dean? Pervert.” But she's still smiling, and her hands leave the back of the seat to slowly undo the button of her shorts. 

That pool of sweat is back, along with another couple puddles in other places along his body. He tries not to let his eyelids fall and his gaze flicker to her busy hands but they do and he fails and when he looks at her face again she's full on grinning at him.

She pulls her pants down just far enough to bring down both flaps of fabric over her legs so her cheap, dollar store underwear are exposed to him. It's fucking sexier than any fancy lingerie and when her hand creeps below the waistband, knuckles bulging against the cotton, bit of her white skin that's never seen the light of day flashed in contrast to her sometimes sunburnt tummy, she sighs and her breath hits his face like a hot desert wind. 

“Sam... Sammy...” He's trying for defiant, stubborn brother but it comes out more like wound up high school boy begging to get to second base in the backseat of his dad's Chevy. 

Her hand moves lower, more of her wrist disappears beneath the waistband and she makes a choked “Ah!” sound, like she's found the treasure buried under the x.

He's frozen solid, toes curled inside his boots and back slack against the hot leather of the car and he couldn't move if someone put the shotgun in the backseat to his head and told him to. He's transfixed by the slide of Sam's hips as her hand works between her legs, slow and steady and he's wondering, not trying to wonder how those hips would work against his own.

Her mouth has turned down from it's devilish grin, now it's slack and open, tongue red beyond her lips and lashes fluttering against her cheeks and she's lost her own game, finished teasing him and lost in the touch of her own hand. He says her name and she tilts her head, licking her lips.

“Sammy... fuck, didn't, I didn't even know you... did...” He chokes, swallows, and she moans.

“Too much, god. Need it, so much.” Slow strokes and she's panting above him and it's better than any fucking porno he'd have to pay for. 

He's only now realizing he's cutting into his own palms, nails marking crescents into his skin and he clenches and unclenches his fists beside his thighs. He won't allow himself to touch her, oh to touch her, but he watches every movement like he's flesh and sweat and bone against her moving form.

“Knew you were watching, wanted you to, oh! Wanted you watching...You're always watching me, Dean.” Her hand grips the headrest behind him, tiny hairs on her arm brushing his cheek and it makes his head swim, makes him realize just how tight his jeans have gotten and just how little it takes for her to drive him crazy.

Cars drive past them and the road continues on forever and his whole world is Sam's hand and what it's busy doing inside his old jeans. 

His hands move of their own accord and end up on her thighs, or as close to her thighs as he'll allow them to get. Fingertips brushing skin and rough, calloused pads catching on stray strands of fabric from the frayed edges of her shorts. She shudders and he swears, face caught in the heat of her neck when she leans down and rests her forehead on the back of the seat.

“Gonna come...” She gasps, inches from his ear, and he bucks up into nothing but imagines it's her, tight and slick and fuck he can hear how wet she is as her fingers dip inside her over and over.

He lets his lips ghost the line of her jaw and he might even taste a drop of her sweat when he licks at his bottom lip. “Fuck, Sammy...baby...”

Another choked sob and finally, his name, and his kid sister is shuddering, coming apart above him on the side of the road of some shit town in the desert. Her ass only touches his lap when she can't hold herself up anymore, spent and breathing heavy against his chest. Her hips twitch a few times against his and he swears, eyes rolling into the back of his head.

His hands are still on her thighs, this time sweaty palm to skin, and he snaps them back like from a burning flame. She's in the passenger seat before he can blink and he's not noticing, inwardly groaning over how she puts her two clever fingers in her mouth and sucks before zipping up her shorts.

The freaky sounding bird yells again and she turns away from him. 

“I gotta take a piss.” He mumbles, losing his grip on the door handle twice before getting it open.

\--

Sam's watching Dean. Her knees are in her face again, feet pressed flat against the glove box and she bites her lip at the picture of him in the sideview, facing digging into his arm as he leans against a dying tree and quickly jerks himself off.

When he comes back she pretends to be asleep, though he knows even she can't sleep through the loud slam of the car door. The Impala starts and rumbles beneath her, and she feels them move back onto the road, the sting of the hot wind on her face. She can feel his eyes running up and down her between miles and she grins against the leather.


End file.
